The Apoptotic Crypt Abscess: An Underappreciated Histologic Finding in Gastrointestinal Pathology.

To differentiate apoptotic crypt abscesses (ACAs) from neutrophilic crypt abscesses (NCAs). Cases with crypt abscesses were classified as containing ACAs, NCAs, or mixed crypt abscesses (MCAs) by H&E staining. Sections were stained with cleaved caspase 3 and myeloperoxidase and recategorized. Fifty-nine cases were reviewed: inflammatory bowel disease (IBD; n = 33), acute cellular rejection (n = 5), graft vs host disease (GVHD; n = 14), cytomegalovirus (n = 5), and drug reaction (n = 2). Concordance was seen in 59%, with most reclassifications resulting from a change of ACAs to MCAs. When cases were classified as having NCA vs those with apoptosis (ACA and MCA), there was 85% agreement (P < .01). NCAs were present in IBD (96%) and not in GVHD or drug injury. Crypt abscesses with apoptosis were seen in 18% of IBD and 96% of non-IBD cases. ACAs and MCAs can be distinguished from NCAs and may be a diagnostically useful finding.